In known damascene type interconnect formation processes, a pattern of cavities is formed in a dielectric layer to correspond to the required pattern of later formed interconnect wirings and contacts. A metal or other conductive material is deposited over the entire surface of the wafer, to sufficient depth to fill all the cavities in the dielectric layer. A mechanical or chemical-mechanical polishing step is then applied to the wafer to remove the conductive material other than that situated within the cavities. Such polishing is the only way to ensure an almost perfectly planar upper surfaces, with the wirings and contacts being flush with the upper surface of the dielectric.
However, the polishing for the removal of such metal is undesirable because a long time is needed to remove a thick metal layer, thus increasing the total processing time required to produce an integrated circuit.
An object of the present invention is to provide a method for forming damascene type wirings and contacts in integrated circuits where the requirement for the polishing of conductive material is reduced or eliminated.
Another object of the present invention is to provide a novel process for forming contacts and interconnect wirings in integrated circuits.
Another object of the present invention is to provide such a process which easily yields contacts and wirings having upper surfaces which are substantially coplanar with surrounding dielectric layers.